Across
1
The number representing nothing
2
Three-sided polygon
4
Closed shape with straight sides
6
Part of a circle's circumference
8
Distance from center to edge of circle
9
Total distance around a shape
10
Comparison of two quantities
Down
2
Line touching circle at one point
3
Line segment connecting two circle points
4
U-shaped curve of a quadratic function
5
System of ordered marks for measuring
7
Number divisible only by 1 and itself
11
Number greater than zero